(1) Field of the Invention
The present invention relates to an electrical switchgear including an air-insulated earthing and disconnecting switch which performs earthing and disconnecting by air insulation.
The present invention also relates to a method for closing, breaking, disconnecting and earthing of voltage/current of the switchgear.
(2) Description of the Related Art
An example of the conventional switchgear will be described with reference to the configuration of the cubicle-type gas-insulated switchgear described in JP-A-6-12948. The switchgear includes a three-position earthing and disconnecting switch with a rotor as a contactor and a vacuum valve in a metal container. One end of the three-position earthing and disconnecting switch is connected to the vacuum valve, and the other end is connected to a high-voltage cable via a bushing bus and a bushing. Further, the other end of the vacuum valve to which the three-position earthing and disconnecting switch is not connected is connected to a bus via the bushing bus and the bushing, and electrically connected to an adjacent switchboard.
In the present configuration, when the rotor of the three-position earthing and disconnecting switch is closed to the bus side and the vacuum valve is further closed, the bus and the cable are electrically continued, and then power is supplied to the cable from the bus.